The invention relates to a tool providing for the automatic exchange of different working fixtures, such tool being adapted particularly for digitally controlled coordinate machine tools.
Previously known systems for the automatic exchange of tools of digitally controlled machine tools reproduce the human handling when changing tools with conventional machine tools. The selection of tools from a program controlled storage container, their removal from the container, their adjustment to a suitably oriented spindle, and their clamping on the spindle of the machine tool are accomplished by means of a number of systems, conveying manipulators, and mechanical hands. All previously known automatic systems for the exchange of tools are controlled by many elements and by many functions designed solely for the exchange of tools. The complicated systems of evaluation of digital informations obtained from working circuits, of auxiliary functions and the acting elements taking part in existing systems causes the automatic exchange of tools to be the most frequent cause of failures of digitally controlled machine tools. The device used in prior systems for clamping tool shafts on the spindle does not allow any connection of additional means, for instance a supply of cooling medium or lubricating medium for the tools and the workpieces. Each tool is provided with a main holder or shaft, with the consequence that individual tools cannot be used on a machine tool with a different clamping spindle.
Previously known tools providing for the exchange of different tool fixtures are arranged so that the connection between the main holder and the tool fixture is accomplished by different bayonet fixtures, or by screw and thread connections. These tools have as their main drawback the fact that the exchange of a tool fixture on a main holder is performed manually. No previously known tool composed of a main holder and a tool fixture, nor any known system of tool fixtures for quick exchange performs the exchange of the tool fixture automatically, without human interference. Such human interference is particularly inonvenient with machines operating in an automatic cycle, since there is the necessity of presence of an attendant of the machine in the case of the manual exchange of tools, and the digitally controlled machine is unable to operate without human presence.